Electric arc start systems and methods

ABSTRACT

A system and methods for electrically starting an arc in a welding process are disclosed. The system and methods may reduce an electromagnetic interference (EMI) footprint during the arc start by reducing the average power spectral density output and broadening the frequency spectrum of the arc EMI footprint. In one embodiment, a welding system may include a welding torch and a welding power source electrically coupled to the welding torch via a weld cable configured to supply electrical energy to the welding torch. The welding power source may include pseudo-random noise (PRN) generator control logic circuitry configured to generate a dithered pulse waveform with a pseudo-randomly selected data sequence of binary values based on one or more baselines, and to apply the dithered pulse waveform to an oscillator during arc starting in a tungsten inert gas (TIG) welding process performed by the welding torch.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of U.S.Provisional Application Ser. No. 62/094,563, entitled “ELECTRIC ARCSTART SYSTEM AND METHOD,” filed Dec. 19, 2014, which is herebyincorporated by reference in its entirety for all purposes.

BACKGROUND

The present disclosure relates generally to welding systems, and, moreparticularly, to starting an arc of certain processes used in thewelding systems.

Some welding systems use arc welding processes, such as gas tungsten arcwelding (GTAW), also known as tungsten inert gas (TIG) welding, where anon-consumable tungsten electrode is used to produce a weld. Weldingsystems that use the TIG welding process may start an arc in severalways, including directly or remotely. Directly starting the arc may bereferred to as a “scratch start.” To scratch start the arc, the tungstenelectrode is scratched against the work with the power on to strike thearc. However, contamination of the weld and the electrode may occurusing scratch starting. Remotely starting the arc may be referred to asa “high frequency (HF) start.” While no contact between the tungstenelectrode and work is made, HF starting the arc may require a relativelyhigh voltage high frequency sinusoidal waveform (a few MHz) to beapplied to the tungsten electrode. The high frequency electric fieldgenerated at the tip of the electrode breaks down the dielectricresistance of the path between the electrode tip and the work piecewithin the column of shielding gas so as to form a conductive path inthe shielding gas so that the arc can be established. Unfortunately, dueto the large output voltage that facilitates the start, HF waveform arcstarts typically create a relatively large electromagnetic interference(EMI) footprint, which may cause problems for nearby electronics, amongother things.

BRIEF DESCRIPTION

Certain embodiments commensurate in scope with the originally claimedsubject matter are summarized below. These embodiments are not intendedto limit the scope of the claimed subject matter, but rather theseembodiments are intended only to provide a brief summary of possibleforms of the subject matter. Indeed, the subject matter may encompass avariety of forms that may be similar to or different from theembodiments set forth below.

In certain embodiments, a welding system may include a welding torch anda welding power source electrically coupled to the welding torch via aweld cable configured to supply electrical energy to the welding torch.The welding power source may include pseudo-random noise (PRN) generatorcontrol logic circuitry configured to generate a dithered pulse waveformwith a pseudo-randomly selected data sequence of binary values based onone or more baselines, and to apply the dithered pulse waveform to anoscillator during arc starting in a tungsten inert gas (TIG) weldingprocess performed by the welding torch.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a block diagram of a TIG welding system including a powersource and a non-consumable tungsten electrode, in accordance with anembodiment of the present disclosure;

FIG. 2 is a block diagram of subcircuitry used to start an arc in theTIG welding system of FIG. 1, in accordance with an embodiment of thepresent disclosure;

FIG. 3 is a flow diagram of a process suitable for starting an arc inthe TIG welding system of FIG. 1, in accordance with an embodiment ofthe present disclosure;

FIG. 4A is an exemplary dithered pulse train including pseudo-randomnoise (PRN) generated using the circuitry of FIG. 2, and FIG. 4B is thebinary representation of the dithered PRN pulse train of FIG. 4A, inaccordance with an embodiment of the present disclosure; and

FIG. 5 is a block diagram of a process suitable for monitoring anddetermining aspects of the TIG welding system of FIG. 1, in accordancewith an embodiment of the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

As previously noted, using high frequency (HF) waveforms to initiate thearc in TIG welding systems may generate a relatively largeelectromagnetic interference (EMI) footprint that is undesirable fornearby electronics. Accordingly, the present disclosure relates toreducing the EMI footprint produced when electrically starting an arc inTIG welding systems using enhanced control circuitry and low costcomponents, among other things. In some embodiments, the enhancedcontrol circuitry, may use a hybrid combination of pulse widthmodulation (PWM) and pulse position modulation (PPM) techniques togenerate a dithering pulse waveform. Any type of ‘pulse’ modulation is asub-class of Amplitude Modulation in which any change in the outputwaveform is a change in amplitude, in the Pulse Modulation case, theamplitude varies from “on” to “off”. The dithering pulse waveform mayreduce the average power spectral density output during a start by theact of spreading the spectrum of frequencies used by the arc startsignal. As described in detail below, the enhanced control circuitry mayachieve PWM by using baselines related to the minimum time an oscillatorneeds to be on to initiate the arc and a maximum time the oscillator canbe off before the arc extinguishes. Other modulation schemes are alsoapplicable to this disclosure. For example, the PRN subcircuitry couldalter, or modulate, either the oscillator phase or frequency. Advantagesof these modes is that the power in the HS Start Waveform is moreconstant (not pulsing on and off) while still spreading the spectrum.

The enhanced control circuitry may use pseudo-random noise (PRN)generator control logic to randomly generate pulse widths in accordancewith the baselines to reduce the average power spectral density. Also,the enhanced control circuitry may dither the pulse position using PPMto broaden the frequency spectrum used to reduce the EMI footprintduring arc starts. Further, in an embodiment, the control circuitry maymonitor the system using the baselines to determine the performance ofthe system and/or whether the electrode is configured properly, amongother things.

Turning now to the drawings, and referring first to FIG. 1, an exemplaryTIG welding system 10 is illustrated as including a power source 12 anda non-consumable tungsten electrode 14. The power source 12 may beelectrically coupled and supply weld power to a torch 16 via a weldcable 17. An operator may hold the torch 16 in one hand and manuallyfeed a filler rod 18 into a weld area. A gas supply 20, which may beintegral with or separate from the power source 12, supplies a gas(e.g., CO₂, argon) to the torch 16 either via the weld cable 17 orthrough a separate cable 21 as illustrated. An operator may engage atrigger 22 of the torch 16 to initiate an arc 24 between the tungstenelectrode 14 and a work piece 26. In some embodiments, the weldingsystem 10 may be triggered by an automation interface, including, butnot limited to, a programmable logic controller (PLC) or robotcontroller. In some embodiments, electromagnetic interference (EMI) thatoften accompanies remote arc starts may be reduced by using pulse widthmodulation (PWM) in conjunction with pulse position modulation (PPM),among other things, to generate a dithered pulse waveform used duringstarting. That is, the disclosed techniques may maintain the peak arcpower to start the arc 24 while reducing the average power spectraldensity that is output, as described in more detail below. The weldingsystem 10 is designed to provide weld power and shielding gas to thewelding torch 16. As will be appreciated by those skilled in the art,the welding torch 16 may be of many different types, and may facilitateuse of various combinations of electrodes 18 and gases.

The welding system 10 may receive data settings from the operator via anoperator interface 28 provided on the power source 12. The operatorinterface 28 may be incorporated into a faceplate of the power source12, and may allow for selection of settings such as the type of start(e.g., dithering pulse waveform, HF, lift-start, etc.), weld process(e.g., TIG, stick, etc.), voltage and current settings, and so forth.The weld settings are communicated to control and power conversioncircuitry 30 within the power source 12.

The control and power conversion circuitry 30 operates to controlgeneration of welding power output that is applied to the electrode 14for carrying out the desired welding operation. That is, the control andpower conversion circuitry 30 controls the current and/or the voltage ofthe weld power supplied to the torch 16. In certain embodiments, thecontrol and power conversion circuitry 30 may include one or moreprocessors 32 that execute computer instructions or access data storedon one or more tangible, non-transitory computer-readable media (e.g.,memory 34). In some embodiments, the control and power conversioncircuitry 30 may include a subcircuitry 36 adapted to regulate a pulseused to start the arc 24 between the electrode 14 and the work piece 26in a TIG welding regime. The subcircuitry 36 may include pseudo-randomnoise (PRN) generator control logic 38, among other things, and thesubcircuitry 36 may be realized by processor 32, which may be anysuitable processor, such as a microcontroller. Using the PRN generatorcontrol logic 38, a dithered pulse waveform may be generated that uses ahybrid combination of PWM and PPM techniques to apply to an oscillator39. According to an aspect, the oscillator 39 may be a crystaloscillator where the operational frequency is known. In someembodiments, any suitable oscillator 39 may be used, such as aresistor-capacitor (RC) oscillator or inductor-capacitor (LC)oscillator. As described in detail below, the average pulse width of thedithered pulse waveform applied to the oscillator 39 affects the averagepower spectral density of the output while the dithering pulse positioncauses a spread spectrum effect. In other words, the average power isreduced while broadening the frequency spectrum of the EMI footprintproduced when starting arcs 24 between the electrode 14 and the workpiece 26.

When determining the dithered pulse train, the subcircuitry 36 mayobtain baselines of the minimum on time of the oscillator 39 needed tostart the arc 24 between the electrode 14 and the work piece 26 and themaximum off time of the oscillator 39 before the arc extinguishes. Insome embodiments, the baselines may be preset and stored in the memory34 of the power source. Additionally or alternatively, the baselines maybe determined at a desired time, such as the first time the arc 24 isstarted, by the subcircuitry 36 measuring the oscillator collector/draincurrent required to start an arc 24 given referenced variables (type ofgas, electrode size and tip pointing, etc.). For example, in someembodiments, the subcircuitry 36 may time, for a referenced value ofoscillator collector/drain current, how long the oscillator 39 is on tostart the arc 24 and setting the minimum on time baseline to that lengthof time and timing how long the oscillator 39 is off before the arc 24extinguishes and setting the maximum off time baseline to that length oftime. The widths of pulses may be randomly generated by activating anddeactivating the oscillator based on the baselines to reduce the averagepower density. Further, in some embodiments, the processor 32 maymonitor the system 10 to determine whether the electrode 14 is properlyconfigured and/or whether the system 10 needs maintenance based at leastin part on the actual on time needed to start the arc 24 and/or theactual length of off time before the arc extinguishes.

The control and power conversion circuitry 30 supplies the weld power(e.g., dithered pulsed waveform) that is applied to the electrode 14 atthe torch 16. The circuitry 30 is coupled to a source of electricalpower as indicated by arrow 34. The power 34 applied to the circuitry 30may originate in the power grid, although other sources of power mayalso be used, such as power generated by an engine-driven generator,batteries, fuel cells or other alternative sources. Power conversioncomponents of the circuitry 30 may include choppers, boost converters,buck converters, inverters, and so forth. In some embodiments,components of the subcircuitry 36 may include an amplifier 40 and atransformer 42, which are described in more detail below.

In some embodiments, the circuitry 30 may monitor the performance of thesystem 10 and the configuration of the electrode 14 using one or moresensors 37. The sensors 37 may be any suitable type of sensor, includingthermal, current, vibration, and so forth. The data fed back to thecircuitry 30 may form a closed loop system, and the circuitry 30 may usethe data to determine various characteristics and configurations of thesystem 10. For example, if a sensor 37 returns data indicating that thearc 24 took longer than the minimum on time baseline for a referencedvalue of oscillator collector/drain current, then the circuitry 30 maydetermine that the electrode 14 is not configured properly (e.g.,positioned incorrectly) and preventative actions may be executed. Thepreventative actions may include generating an audio and/or visual alertvia the operator interface 28. Further, if the arc 24 extinguishesquicker or shorter than the maximum off time baseline after turning offthe power source 12, then the processor 32 may determine that theelectrode 14 is improperly configured. In some embodiments, the currentin the amplifier 40 of the subcircuitry 36 may be monitored to surmisethe quality of the electrode 14. For example, if more than a thresholdamount of current is needed to start the arc 24, then the processor 32may determine that the quality of the electrode 14 has degraded andgenerate an alert via the operator interface 28.

FIG. 2 is a block diagram of subcircuitry 36 used to start an arc in theTIG welding system 10 of FIG. 1, in accordance with an embodiment of thepresent disclosure. As depicted, in certain embodiments, thesubcircuitry 36 may include four elements: PRN generator control logic38, an oscillator 39, an amplifier 40, a transformer 42, and a powersupply subsystem 44. The PRN generator control logic 38 may beimplemented in hardware and/or software. That is, the PRN generatorcontrol logic 38 may be implemented as a circuit, such as afield-programmable gate array (FPGA), or as computer-instructions(program) stored in one or more tangible, non-transitoryprocessor-readable media and executed by a microprocessor ormicrocontroller, or the like. As previously noted, the PRN generatorcontrol logic 38 is configured to generate a dithered pulse train toapply to the oscillator 39 to provide regulated power to start the arc24 with a reduced EMI footprint. In certain embodiments, the oscillator39 may be part of the PRN generator control logic 38. The EMI may bereduced by spreading the spectrum of frequencies used by the outputsignal and reducing the average power output. Spreading the spectrum offrequencies may be enabled by varying the temporal positions of pulses(e.g., via PPM) in accordance with characteristics of the modulatingsignal and reducing the average power may be enabled by varying thewidths of the pulses (e.g., via PWM). To achieve these aspects, the PRNgenerator 38 may generate a pseudo-random data sequence of binary values(logical 1's and 0's) to apply to a state variable of the oscillator 39.The state variable of the oscillator 39 is either on (1) or off (0). ThePRN generator control logic 38 may obtain baselines for the minimum timethe oscillator 39 needs to be on to initiate the arc 24 and the maximumtime the oscillator 39 may be off before the arc 24 extinguishes.

In some embodiments, the baselines may be preprogrammed and obtainedfrom the memory 34. Additionally or alternatively, the baselines may beobtained upon activation of the power source 12 by determining, for areferenced value of oscillator collector/drain current, how long theoscillator 39 was on to start the arc 24 (e.g., based on data returnedby sensors 37) and then turning off the oscillator 39 and determininghow long it takes for the arc 24 to extinguish. The determined baselinesmay be stored in the memory 34 for later access. In any embodiment, oncethe baselines are obtained, the PRN generator control logic 38 maygenerate random values in between the minimum and maximum values. Thatis, the minimum on time and maximum off time may establish a range oftimes to which the intermediate values may be set. Thus, the datasequence generated is pseudo-random because the initial values (logical1's) for starting the arc 24 are determined based on the minimum on timebaseline and the final values (logical 0's) for extinguishing the arc 24are determined based on the maximum off time baseline, while the valuesin between are determined randomly according to the baselines. Forexample, the PRN generator control logic 38 may choose a data sequencesuch that the oscillator 39 stays on long enough to get the arc 24started and not off long enough so that the arc 24 extinguishes. Itshould be noted that the generation of the data sequence to apply to theoscillator's state variable may be based on the duty cycle. By randomlysetting the length of times the oscillator 39 is on and off in betweenthe minimum on time and maximum off time, the widths of the pulses arevaried (PWM) and the positions of the pulses are varied (PPM), therebyreducing the average power spectral density (EMI footprint).

In certain embodiments, the amplifier 40 may be a radio-frequency RFamplifier and embody a high efficiency topology, such as class F, butany suitable class may be used, such as class A, AB, B, C, D, E, F, etc.In certain embodiments, the amplifier 40 may include class C, D, E, F,or any other amplifier topology which offers improvement in efficiencyas compared to a class A amplifier. The high efficiency topologypromotes lower power rating and lower cost to manufacture. For example,using the high efficiency amplifier 40 may enable using lower powercomponents, such as low voltage metal-oxide-semiconductor field-effecttransistors (MOSFETs). Also, the amplifier 40 may be non-tuned, whichfacilitates the generation of broad band signals used to achieve the EMIspread spectrum effect. That is, being non-tuned may mean the amplifier40 is not tuned to output signals at a particular frequency. As aresult, the non-tuned feature of the amplifier 40 may enable theamplifier 40 to output signals at different frequencies in the frequencyspectrum. The amplifier 40 may receive low voltage signals as input andoutput signals with higher voltages. In addition, the power supplysubsystem 44 may provide filtered power to the PRN generator controllogic 38 and the amplifier 40 for the subcircuitry 36.

As may be appreciated by those skilled in the art, Q may refer toquality factor and the higher the Q, the narrower the bandwidth, and thelower the Q, the broader the bandwidth. Thus, the transformer 42 may below Q tuned to achieve broad band operation while providing frequencyfiltering. For example, in certain embodiments, the transformer 42 mayhave a Q of approximately 1.0 (e.g., greater than approximately 0.5and/or less than approximately 4.0). A shunt capacitor may be used onthe transformer 42 primary winding, which in combination with parasiticelements, enables the low Q tuned characteristic of the transformer 42.The transformer 42 may output the power to the torch 16, represented byarrow 46. Using the broad band RF amplifier 40 with the low Q tunedtransformer on the output stage enables a lower voltage rating on thecircuitry 30, while still outputting voltage high enough to start thearc 24.

FIG. 3 is a flow diagram of a process 50 suitable for starting the arc24 in the TIG welding system 10 of FIG. 1, in accordance with anembodiment of the present disclosure. The process 50 may be implementedand executed by the subcircuitry 36 of FIG. 2. The process 50 mayinclude obtaining baselines for minimum oscillator on time to start thearc 24 in a welding process performed by the TIG welding system 10 andmaximum oscillator off time before the arc 24 extinguishes (processblock 52), generating a dithered pseudo-random noise (PRN) pulse trainin accordance with the baselines using PWM and PPM (process block 54),and applying the PRN pulse train to the oscillator's state variableduring arc starting in the welding process performed by the weldingsystem (process block 56). For example, in certain embodiments, a phaseof the oscillator 39 may be altered (e.g., modulated) based at least inpart on the generated PRN pulse train. In addition, in certainembodiments, a frequency of the oscillator 39 may be altered (e.g.,modulated) based at least in part on the generated PRN pulse train. Aspreviously discussed, regarding process block 52, the baselines that maybe used relate to the minimum time the oscillator 39 needs to be on tostart the arc 24 and the maximum time the oscillator 39 can be offbefore the arc 24 extinguishes.

Obtaining the baselines may include accessing the baselines stored inthe memory 34 or generating the baselines anew while the power source 12is operational. Indeed, the baselines may be adapted as the system 10 isused due to normal usage. For example, the minimum amount of time thatthe oscillator 39 needs to be on to initiate the arc 24 may increase asthe electrode 14 quality changes. As such, baselines may bereestablished at any desired time. In some embodiments, the baselinesmay be determined upon the first arc 24 initiated by the system 10. Thebaselines may be updated periodically (e.g., every day, week, month,etc.). Also, when the configuration of the electrode 14 changes, thebaselines may be reestablished. For example, in certain embodiments,when a new tungsten insert is installed in the torch 16, new baselinesmay be determined. After the baselines are determined, they may bestored in the memory 34 until they are updated again.

In process block 54, generating the dithered PRN pulse train inaccordance with the baselines may include selecting a data sequence suchthat the oscillator 39 stays on long enough to get the arc 24 startedand not off long enough so the arc 24 extinguishes. As noted above, thedata may include binary values (logical 1's and 0's) and may be based onthe duty cycle. The data sequence may maintain the peak arc power whilereducing the average power spectral density. The data sequence may notbe completely random because the data sequence is generated within thebounds of the baselines. For example, the data sequence generated maybegin with 1's for as long as needed to start the arc 24. Then, the datasequence may select random 1's or 0's according to the baselines. Thatis, any number of consecutive 1's may be selected for at least theminimum on time and any number of consecutive 0's may be selected lessthan the maximum off time. Last, when it is desired to extinguish thearc 24, consecutive 0's may be selected for the maximum off time so thearc 24 extinguishes. By randomly selecting values in the dithered PRNpulse train, the pulse widths (e.g., via PWM) and the temporal positionof the pulses (e.g., via PPM) are varied, leading to a spread spectrumeffect and a reduced average power spectral density. Once the ditheredPRN pulse train is generated, it may be applied to the state variable ofthe oscillator 39 to control the operation of the oscillator 39accordingly (process block 56).

FIG. 4A is an exemplary dithered pulse train 60 including pseudo-randomnoise (PRN) generated using the subcircuitry 36 of FIG. 2, and FIG. 4Bis a binary representation of the dithered PRN pulse train 60 of FIG.4A, in accordance with an embodiment of the present disclosure. Startingwith FIG. 4A, as depicted, the generated dithered PRN pulse train 60adheres to the baselines for the minimum on time and the maximum offtime. It should be noted that the time lengths represented are forexplanatory purposes and actual lengths and binary values may differaccordingly. For example, in the depicted embodiment, the minimum ontime to start the arc 24 is set to 3 milliseconds (ms) and the maximumoff time before the arc 24 extinguishes is set to 7 ms. Accordingly, thepulse train 60 begins by setting the state variable to high (logical1's) for the minimum amount of time needed to start the arc 24 (3 ms).After the arc 24 is started at time t₁, the state variable changesrandomly between on (logical 1) and off (logical 0) within the bounds ofthe baselines. Specifically, the state variable is set accordingly:

-   0 for 6 ms, which is less than the maximum off time of 7 ms-   1 for 3 ms, which is the minimum on time baseline-   0 for 2 ms, which is less than the maximum off time of 7 ms-   1 for 5 ms, which is greater than the minimum on time baseline-   1 for 4 ms, which is greater than the minimum on time baseline-   0 for 3 ms, which is less than the maximum off time of 7 ms-   1 for 9 ms, which is greater than the minimum on time baseline

Then, at time t₂, when it is desired to extinguish the arc, the statevariable is set to 0 for the maximum off time of 7 ms so the arcextinguishes at time t₃. The resulting data sequence of binary valuesfor the dithered PRN pulse train 60 is shown in FIG. 4B. For example,the sequence is represented as:

-   -   11100000011100111110000011110001111111110000000

As may be seen, the widths of the pulses vary. Indeed, the on times ofthe pulses equal 3 ms, 3 ms, 5 ms, 4 ms, and 9 ms. Also, the positionsof when the pulses activate vary between cycles to spread thefrequencies used by the signal. The spread spectrum effect may befurther enabled by the non-tuned amplifier 40 and low Q transformer 42configured to provide broad band operation. The average power may bereduced by randomly varying pulse widths because the output power isaveraged between all the pulses instead of kept constant with a highvoltage as is done in HF waveform arc starts.

FIG. 5 is a block diagram of a process 70 suitable for monitoring anddetermining aspects of the TIG welding system 10 of FIG. 1, inaccordance with an embodiment of the present disclosure. The process 70may be implemented as computer instructions stored on the one or morememories 34 and executable by the one or more processors 32. The process70 may include monitoring the system 10 (process block 72), determiningwhether the system 10 is configured properly (process block 74), anddetermining the performance of the system 10 and/or quality of theelectrode 14 (process block 76). Specifically, in process block 72,monitoring the system 10 may include using the sensors 37 to monitordesired aspects of the welding process. For example, in someembodiments, the sensors 37 may be configured to track the amount oftime elapsed to start the arc 24 and the amount of time elapsed toextinguish the arc 24. The sensors 37 may be configured to send thetracked data back to the control and power conversion circuitry 30. Insome embodiments, the sensors 37 may detect the voltage and current sentto the torch 16 from the circuitry 30, thermal properties of theelectrode 14 (e.g., heat of electrode during operation), and so forth.

Using the data returned from the sensors 37 or data in the possession ofthe circuitry 30, the processor 32 may determine whether the system 10is configured properly (process block 72). For example, the type of weld(e.g., TIG) determines how the electrode 14 is pointed and positioned.If the data indicates that the electrode 14 is taking longer than thebaseline for the minimum on time to start the arc 24, then the processor32 may determine that the electrode 14 is not properly positioned.Additionally or alternatively, if the arc 24 starts and thenextinguishes before the baseline for the maximum off time, then theprocessor 32 may determine that the electrode 14 is not pointedproperly. In this way, the process 70 may use the baselines to performself-diagnostics.

In addition, the process 70 may include determining the performanceand/or quality of aspects of the system 10 (process block 76). Forexample, if the current required to initiate the arc 24 increases beyonda set threshold value (e.g. maximum value), the processor 32 maydetermine that the quality of the electrode 14 is decaying, requiringthat the electrode be re-pointed or shaped for the desired weld process.In other words, the processor 32 may determine that the electrode 14 isconfigured inccorrectly based at least in part on whether, for a givenoscillator collector/drain current, the time to initiate an arc exceedsa normative time threshold based upon the baselines. As such, thecurrent may be monitored in the circuitry 30 to determine how muchvoltage is needed to initiate the arc 24. Also, the sensors 37 maymonitor the current supplied to the torch 16. In some embodiments, theperformance or quality of the electrode 14 may be assessed by one ormore electrical characteristics of the subcircuitry 36 such that thosecharacteristics are compared against normative limits of operation.

In any of the above described scenarios with regards to process block 74and/or process block 76, if the processor 32 determines that there is aconfiguration issue or quality concern, an alert may be generated viathe operator interface 28. As a result, the process 70 may providenotice to the user that the electrode 14 is not configured properly, orneeds to be replaced or re-shaped/pointed, for example.

While only certain features of the disclosed subject matter have beenillustrated and described herein, many modifications and changes willoccur to those skilled in the art. It is, therefore, to be understoodthat the appended claims are intended to cover all such modificationsand changes as fall within the true spirit of the disclosure.

1. A welding system, comprising: a welding torch; and a welding powersource coupled to the welding torch via a weld cable configured tosupply welding power to the welding torch, wherein the welding powersource comprises: pseudo-random noise (PRN) generator control logiccircuitry configured to generate a dithered pulse waveform with apseudo-randomly selected data sequence of binary values, and to applythe dithered pulse waveform to an oscillator during arc starting in atungsten inert gas (TIG) welding process performed by the welding torch.2. The welding system of claim 1, wherein the dithered pulse waveform isgenerated based at least in part on one or more baselines comprising aminimum on time baseline for the oscillator to start an arc and amaximum off time baseline for the oscillator before an arc extinguishes.3. The welding system of claim 2, wherein the pseudo-randomly selecteddata sequence of binary values comprises initial binary values set to onfor the minimum on time according to the baselines for the oscillator tostart the arc, intermediary binary values set to on for random lengthsof time greater than the minimum on time baseline and intermediarybinary values set to off for random lengths of time less than themaximum off time baseline, and final binary values set to off for themaximum off time according to the baselines.
 4. The welding system ofclaim 1, wherein the dithered pulse waveform reduces an average powerspectral density output due to random width pulses and causes a spreadfrequency spectrum effect due to random temporal positions of pulses ofthe dithered pulse waveform.
 5. The welding system of claim 1, whereinthe welding power source comprises a low Q transformer configured toprovide broad band operation and to filter frequencies of output powerfrom the welding power source.
 6. The welding system of claim 1, whereinthe welding power source comprises a non-tuned RF amplifier configuredto provide broad band operation.
 7. The welding system of claim 6,wherein the non-tuned RF amplifier embodies a high efficiency amplifiertopology comprising class C, D, E, or F.
 8. A welding system,comprising: a welding torch; and a welding power source coupled to thewelding torch via a weld cable configured to supply welding power to thewelding torch, wherein the welding power source comprises: pseudo-randomnoise (PRN) generator control logic circuitry configured to generate apulse waveform with a pseudo-randomly selected data sequence of binaryvalues, and to alter a phase of an oscillator during arc starting in atungsten inert gas (TIG) welding process performed by the welding torchbased at least in part on the pulse waveform.
 9. The welding system ofclaim 8, wherein the pulse waveform reduces an average power spectraldensity output due to random width pulses and causes a spread frequencyspectrum effect due to random temporal positions of pulses of the pulsewaveform.
 10. The welding system of claim 8, wherein the welding powersource comprises a low Q transformer configured to provide broad bandoperation and to filter frequencies of output power from the weldingpower source.
 11. The welding system of claim 8, wherein the weldingpower source comprises a non-tuned RF amplifier configured to providebroad band operation.
 12. A welding system, comprising: a welding torch;and a welding power source coupled to the welding torch via a weld cableconfigured to supply welding power to the welding torch, wherein thewelding power source comprises: pseudo-random noise (PRN) generatorcontrol logic circuitry configured to generate a pulse waveform with apseudo-randomly selected data sequence of binary values, and to alter afrequency of an oscillator during arc starting in a tungsten inert gas(TIG) welding process performed by the welding torch based at least inpart on the pulse waveform.
 13. The welding system of claim 12, whereinthe pulse waveform reduces an average power spectral density output dueto random width pulses and causes a spread frequency spectrum effect dueto random temporal positions of pulses of the pulse waveform.
 14. Thewelding system of claim 12, wherein the welding power source comprises alow Q transformer configured to provide broad band operation and tofilter frequencies of output power from the welding power source. 15.The welding system of claim 12, wherein the welding power sourcecomprises a non-tuned RF amplifier configured to provide broad bandoperation.
 16. A welding system, comprising: a welding torch; and awelding power source coupled to the welding torch via a weld cableconfigured to supply welding power to the welding torch, wherein thewelding power source comprises: pseudo-random noise (PRN) generatorcontrol logic circuitry configured to generate a pulse positionmodulated (PPM) waveform with a pseudo-randomly selected data sequenceof binary values, and to alter a phase of an oscillator during arcstarting in a tungsten inert gas (TIG) welding process performed by thewelding torch based at least in part on the PPM waveform.
 17. Thewelding system of claim 16, wherein the PPM waveform reduces an averagepower spectral density output due to random width pulses and causes aspread frequency spectrum effect due to random temporal positions ofpulses of the PPM waveform.
 18. The welding system of claim 16, whereinthe welding power source comprises a low Q transformer configured toprovide broad band operation and to filter frequencies of output powerfrom the welding power source.
 19. The welding system of claim 16,wherein the welding power source comprises a non-tuned RF amplifierconfigured to provide broad band operation.
 20. A welding system,comprising: a welding torch; and a welding power source coupled to thewelding torch via a weld cable configured to supply welding power to thewelding torch, wherein the welding power source comprises: pseudo-randomnoise (PRN) generator control logic circuitry configured to generate apulse width modulated (PWM) waveform with a pseudo-randomly selecteddata sequence of binary values, and to alter a phase of an oscillatorduring arc starting in a tungsten inert gas (TIG) welding processperformed by the welding torch based at least in part on the PWMwaveform.
 21. The welding system of claim 20, wherein the PWM waveformreduces an average power spectral density output due to random widthpulses and causes a spread frequency spectrum effect due to randomtemporal positions of pulses of the PWM waveform.
 22. The welding systemof claim 20, wherein the welding power source comprises a low Qtransformer configured to provide broad band operation and to filterfrequencies of output power from the welding power source.
 23. Thewelding system of claim 20, wherein the welding power source comprises anon-tuned RF amplifier configured to provide broad band operation.